Human Genetic Disorders Autosomal Recessive Sickle-cell disease

I. Human Genetic Disorders

A. Autosomal Recessive3. Sickle-cell disease

• Single amino acid substitution (valine for glutamate) in hemoglobin

• Causes some erythrocytes to form sickle shape• Abnormal erythrocytes slow blood flow and may block

capillaries

A. Autosomal Recessive3. Sickle-cell disease

• Single amino acid substitution (valine for glutamate) in hemoglobin

• Causes some erythrocytes to form sickle shape• Abnormal erythrocytes slow blood flow and may block

capillaries• Most common in people of African descent (1 in 10

African Americans is heterozygous – “sickle cell trait”)• Why so common?

• May be advantageous in areas where malaria is a problem• Heterozygous people more resistant to malaria

than homozygous dominant people

Fig. 23.17

http://upload.wikimedia.org/wikipedia/commons/1/10/Malaria_versus_sickle-cell_trait_distributions.png

Malaria Sickle Cell Allele Frequency

http://www.cdc.gov/malaria/about/biology/sickle_cell.html

A. Autosomal Recessive4. Tay-Sachs disease

• Absence in brain of enzyme that helps to break down membrane lipids and prevents their accumulation• Accumulation causes brain damage

• Especially common in people of Ashkenazi Jewish (Eastern European) descent• Possibly due to population bottleneck during

persecution & restriction to ghettos in Middle Ages

B. Autosomal Dominant1. Achondroplasia

• Abnormal gene on chromosome 4 skeletal growth disorder dwarfism (relatively normal torso, short arms and legs)

• Most common growth-related disorder• Results from inheritance in <20% of cases

2. Huntington’s Disease• Defective allele proteins with long glutamine strands• Affects nervous system severe mental and physical

deterioration death• Typically appears later in life – Almost always before

age 50 but almost never before age 20• Usually after reproductive age

II. Chromosomal Theory of Inheritance

• Proposed in early 1900s• Unified understanding of mitosis and

meiosis with Mendel’s work on inheritance

Fig. 15.2

III. Linkage and Recombination

A. Linkage• Alleles don’t always assort independently

• Two genes on same homologous chromosome• Linkage first studied in Drosophila by

Thomas Morgan (early 1900s)• Worked with wild type and mutant fruit flies

• Studied inheritance with two-point test cross between heterozygous individual and homozygous recessive individual

Fig. 15.9

B. Recombination• Occurs during crossing over in meiosis• Drosophila example

• F1 parent produced some recombinant gametes

Fig.15.10

B. Recombination• Greater distance between genes

Greater probability of recombination• Distance between two genes expressed in

map units• 1 map unit = 1% recombination frequency

Fig. 15.11

Human Genetic Disorders Autosomal Recessive Sickle-cell disease

Documents

Transcript of Human Genetic Disorders Autosomal Recessive Sickle-cell disease

versie V2 (390 genen) Centrum voor Medische Genetica Gent · ataxia and seizures, 618170 (3), Autosomal recessive AFG3L2 604581 Spastic ataxia 5, autosomal recessive, 614487 (3),

Novel mutations in PIEZO1 cause an autosomal recessive ...openaccess.sgul.ac.uk/107589/1/Novel mutations in... · Novel mutations in PIEZO1 cause an autosomal recessive generalized

Prevalence of genetic disease Type of genetic disease Prevalence per 1000 1. Single gene (Mendelian) Autosomal dominant Autosomal recessive X linked recessive.

Autosomal recessive ichthyosis with limb reduction defect ... · including autosomal dominant, autosomal recessive and X-linked inheritance [1,2]. Associated cutaneous and extracutaneous

Autosomal recessive GJA1 (Cx43) gene mutations cause … · recent clinical presentations and genetic screens have revealed two (R76H and R33X) autosomal recessive mutations linked

Mutations in GRHL2 Result in an Autosomal-Recessive Ectodermal Dysplasia Syndrome · REPORT Mutations in GRHL2 Result in an Autosomal-Recessive Ectodermal Dysplasia Syndrome Gabriela

Principles of Inheritance and Variation...Select the autosomal dominant, autosomal recessive, X-sex linked recessive and Y-sex linked recessive disorders respectively (A) Myotonic

AutosomAl recessive AtAxiAs - SciELO · KEY WORDS: autosomal recessive ataxias, cerebellar ataxia, cerebellum, Friedreich ataxia. Ataxias autossômicas recessivas: 20 tipos e muito

Autosomal Recessive NRL Mutations in Patients with ...

Topical polyhydroxy acid treatment for autosomal recessive ...

Autosomal Recessive Polycystic Kidney Disease (ARPKD) The disease ...

GROUP A 1.jenniwilkening.weebly.com/.../9/6/2/7/9627483/genetics_problems_split_up_into_groups.pdfGROUP E 1. Sickle-cell anemia is an autosomal recessive (aa) genetic disorder that

Autosomal Dominant and Recessive Osteochondrodysplasias ...

Outline - mcb.berkeley.edu · screening Reading: pp 200-202, 316 Outline Autosomal recessive genetic diseases Screening Autosomal recessive ... developmental retardation, followed

The Skeletal Muscle Chloride Channel in Dominant Recessive ...causedominantor recessive myotonia. Autosomal recessive generalized myotonia (GM) is a nondystrophic disorder ofskele-tal

Clinical features and molecular genetics of autosomal recessive …sswang/CB-nonmotor/fogel... · 2011. 3. 8. · Clinical features and molecular genetics of autosomal recessive cerebellar

Evidence for autosomal recessive inheritance cerebral ... · Evidencefor autosomal recessive inheritance in cerebralgigantism 159 TABLE I ANTHROPOMETRICDATA Head 1-Age Weight(g) Length(cm)

Systematic review of autosomal recessive ataxias and ......REVIEW Open Access Systematic review of autosomal recessive ataxias and proposal for a classification Marie Beaudin1, Christopher

Genomics BIT 220 Chapter 21. Basic Terminology Autosomes vs Sex Chromosomes Autosomal Recessive need 2 copies of gene Sickle-Cell Anemia Cystic Fibrosis.

Autosomal dominant autosomal recessive X-linked …bogari.net/Bogari/Medical_Genetics_files/2-2 Patterens of...• Autosomal dominant • autosomal recessive • X-linked dominant